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TARG(4) FreeBSD Kernel Interfaces Manual TARG(4)
NAMEtarg -- SCSI target emulator driver
SYNOPSIS
To compile this driver into the kernel, place the following line in your
kernel configuration file:
devicetargDESCRIPTION
The targ driver provides an interface for usermode programs to emulate
SCSI target devices. A sample program that emulates a disk drive (simi-
lar to da(4)) can be found in /usr/share/examples/scsi_target.
The targ driver supplies the control device /dev/targ. After opening the
device, the file descriptor must be bound to a specific bus/target/LUN
and enabled to process CCBs using the TARGIOCENABLE ioctl. The process
then uses write(2) to send CCBs to the SIM and poll(2) or kqueue(2) to
see if responses are ready. Pointers to completed CCBs are returned via
read(2). Any data transfers requested by the user CCBs are done via
zero-copy IO.
IOCTLS
The following ioctl(2) calls are defined in the header file
<cam/scsi/scsi_targetio.h>.
TARGIOCENABLE (structioc_enable_lun) Enable target mode on the LUN
specified by the following structure:
struct ioc_enable_lun {
path_id_t path_id;
target_id_t target_id;
lun_id_t lun_id;
int grp6_len;
int grp7_len;
};
The selected path (bus), target, and LUN must not already
be in use or EADDRINUSE is returned. If grp6_len or
grp7_len are non-zero, reception of vendor-specific com-
mands is enabled.
TARGIOCDISABLE Disable target mode and abort all pending CCBs. The CCBs
may optionally be read as they complete. TARGIOCENABLE
can then be called to activate a different LUN. Multiple
disable calls have no effect. The close(2) system call
automatically disables target mode if enabled.
TARGIOCDEBUG (int) Enables CAM_PERIPH debugging if the argument is
non-zero, otherwise disables it.
FILES
<cam/scsi/scsi_targetio.h> describes the usermode interface.
/sys/cam/scsi/scsi_target.c is the driver source file.
/dev/targ is the control device.
SEE ALSO/usr/share/examples/scsi_target, ahc(4), isp(4), scsi(4)FreeBSDTargetInformation, http://www.root.org/~nate/freebsd/.AUTHORS
The targ driver first appeared in FreeBSD 3.0 and was written by Justin
T. Gibbs. It was rewritten for FreeBSD 5.0 by Nate Lawson
<nate@root.org>.
BUGS
Currently, only the ahc(4) and isp(4) drivers fully support target mode.
The ahc(4) driver does not support tagged queuing in target mode.
FreeBSD 10.2 December 13, 2011 FreeBSD 10.2